A Gran Blood test checks for a high level of granulocytes in the blood (=Granulocytosis). Granulocytosis occurs when there are too many granulocytes (a form of white blood cells) in the blood. Examples of granulocytes are neutrophils, eosinophils and basophils. Neutrophils make up the largest percentage of granulocytes.
All of them form in the bone marrow where stem cells develop into different types of blood cells. Granulocytes circulate through the blood and respond to signals from the immune system, for example to attack foreign substances that are responsible for inflammation or infections.
An increase in the number of granulocytes occurs in response to infections, autoimmune diseases, and blood cell cancers. An abnormally high white blood cell count usually indicates an infection or disease.